Previous studies [Burdick,et al., J. Acoust. Soc. Am.64, (1978)] found that chinchillas exposed to octave bands of noise centered at 63 and 1000 Hz incur maximum hearing loss at the frequencies of 1400 and 2000 Hz. Since these bands of noise produce maximum hearing loss at the same frequencies, the question arose concerning the possibility of synergistic effects when exposed to both bands of noise simultaneously. Three groups of chinchillas were exposed to these noise bands for nine days. One group was exposed for four and one‐half days to the low‐frequency noise followed by four and one‐half days of exposure to the high‐frequency noise; another group was exposed to the same noise bands with the order of presentation reversed. The third group of animals was exposed to both noise bands simultaneously. The intensity level of each noise band was 94 dBA. No interactive effects were produced either by the successive exposures or by the simultaneous exposure.